Chair back



FIG. 1 is a perspective view of a chair back of the present invention;

FIG. 2 is a side elevational view of the chair back of FIG. 1, the opposite side being a mirror image thereof;

FIG. 3 is a front elevational view of the chair back of FIGS. 1 and 2;

FIG. 4 is a rear elevational view of the chair back of FIGS. 1-3;

FIG. 5 is a top view of the chair back of FIGS. 1-4; and,

FIG. 6 is a bottom view of the chair back of FIGS. 1-6.

The broken lines shown in the Figures are for environmental purposes only and form no part of the claimed design. 

The ornamental design for a chair back, as shown and described. 